 var keyStr = "ABCDEFGHIJKLMNOP" +
	               "QRSTUVWXYZabcdef" +
	               "ghijklmnopqrstuv" +
	               "wxyz0123456789+/" +
	               "=";
	  /* Ham ma hoa */   
	  function en64(input) {
	     input = escape(input);
	     var output = "";
	     var chr1, chr2, chr3 = "";
	     var enc1, enc2, enc3, enc4 = "";
	     var i = 0;
	 
	     do {
	        chr1 = input.charCodeAt(i++);
	        chr2 = input.charCodeAt(i++);
	        chr3 = input.charCodeAt(i++);
	 
	        enc1 = chr1 >> 2;
	        enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
	        enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
	        enc4 = chr3 & 63;
	 
	        if (isNaN(chr2)) {
	           enc3 = enc4 = 64;
	        } else if (isNaN(chr3)) {
	           enc4 = 64;
	        }
	 
	        output = output +
	           keyStr.charAt(enc1) +
	           keyStr.charAt(enc2) +
	           keyStr.charAt(enc3) +
	           keyStr.charAt(enc4);
	        chr1 = chr2 = chr3 = "";
	        enc1 = enc2 = enc3 = enc4 = "";
	     } while (i < input.length);
	 
	     return output;
	  }


	  /* Ham giai ma */
	  function de64(input) {
	     var output = "";
	     var chr1, chr2, chr3 = "";
	     var enc1, enc2, enc3, enc4 = "";
	     var i = 0;
	 
	     // remove all characters that are not A-Z, a-z, 0-9, +, /, or =
	     var base64test = /[^A-Za-z0-9\+\/\=]/g;
	     if (base64test.exec(input)) {
	        alert("There were invalid base64 characters in the input text.\n" +
	              "Valid base64 characters are A-Z, a-z, 0-9, '+', '/',and '='\n" +
	              "Expect errors in decoding.");
	     }
	     input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
	 
	     do {
	        enc1 = keyStr.indexOf(input.charAt(i++));
	        enc2 = keyStr.indexOf(input.charAt(i++));
	        enc3 = keyStr.indexOf(input.charAt(i++));
	        enc4 = keyStr.indexOf(input.charAt(i++));
	 
	        chr1 = (enc1 << 2) | (enc2 >> 4);
	        chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
	        chr3 = ((enc3 & 3) << 6) | enc4;
	 
	        output = output + String.fromCharCode(chr1);
	 
	        if (enc3 != 64) {
	           output = output + String.fromCharCode(chr2);
	        }
	        if (enc4 != 64) {
	           output = output + String.fromCharCode(chr3);
	        }
	 
	        chr1 = chr2 = chr3 = "";
	        enc1 = enc2 = enc3 = enc4 = "";
	 
	     } while (i < input.length);
	 
	     return unescape(output);
	  }

